Question: What is the chemical compound of the drug used to treat bipolar disorder
Paraphrase: What is the drug's chemical compound used to treat bipolar disorder?
SPARQL (Wikidata):  select distinct ?sbj where { ?sbj wdt:P2175 wd:Q131755 . ?sbj wdt:P31 wd:Q11173 } 
Answer: olanzapine, topiramate, clozapine, valproic acid, clonazepam, quetiapine, lamotrigine, gabapentin, carbamazepin, risperidone, tiagabine, transclopenthixol